Design of steel and composite bridges Highway bridges

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012 1 Design of steel and composite bridges Highway bridges Joël Raoul Seminar ‘B...
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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Design of steel and composite bridges Highway bridges Joël Raoul

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Main selected features

• General presentation and scope of EC3 and • • • • •

EC4 related to steel and composite bridges Materials Structural analysis Cross-section analysis at ULS and SLS Treatment of instabilities Fatigue

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

application s

Partie 2

bridges Partie 7.1

pylons

Partie 7.2

chimneys Partie 6

Cranes

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Partie 4.1

Partie 4.2

Silos

tanks

Partie 4.3

Partie 5

Pipelines

piling

Partie 1.1

General rules

Partie 1.7

Plated elements loaded transv.

Partie 1.2

fire

Partie 1.8

joints

Partie 1.3

sheetings

Partie 1.9

Fatigue

Partie 1.4

Stainless steel

Partie 1.10

Brittle fracture

Partie 1.5

Plated elements

Partie 1.11

cables

Partie 1.6

shells

Partie 1.12

generic rules

S500 to S690

Eurocode 3 : steel structures

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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EN 1994 : composite steel-concrete structures EN 1994-2 general rules and bridges (self-sufficient)

CONCRETE PART

STEEL PART

EN 1992-2

EN 1993-2

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Scope of EN1993-2 All steel bridges (in general with an orthotropic deck) and the steel part of composite bridges

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Scope of EN1994-2 Composite bridges

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Girder bridges

Economy : two-girder bridges even for 2X2 lanes due to robustness rules

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Box girders

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Composite members

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Tension members (tie of bowstring arch)

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Composite plates

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Filler beam decks In the transversal direction

In the longitudinal direction

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Materials Concrete : Between C20 and C60 for composite bridges (C 90 for concrete bridges)

Steel : up to S460 for steel and composite bridges (S 500 to S 700 in a separate part 1-12 for steel bridges)

Choice of material : avoid brittle behaviour

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

HOAN BRIDGE 2000

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

• An overlooked defect is assumed during execution : e.g. : a = 2.2 mm for tf=80 mm

• It grows acc. to fracture mechanics laws (assuming fatigue is governing the design)

• Up to the critical defect depending on Charpy energy at service temperature

• Over a period depending on the inspection periodicity

NOTE: fabrication rules and quality plan are given in EN 1090 They are assumed to be met when using EN 1993

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

EN 10025

grade quality

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Structural analysis

Elastic

Plastic (buildings, bridges in accidental situations)

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Classes of steel cross-sections Cl.1 Cl.2

Mpl

Cl.3 Mel

Cl.4  1

3

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Class of flanges

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Global analysis of composite bridges: two aspects are considered

Cracking of concrete on support Non linear behaviour at mid span Mpl,Rd Mel,Rd

Class 1



Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Modular ratio used in a composite section n L  n0 . 1  Lt  n0 

Ea E cm

Value of t0 :

and



t    t  t 0  creep coefficient given by EC2 :

t0 = 1 day for shrinkage t0 = a mean value in case of concrete cast in several stages SIMPLE CALCULATIONS

 L is given by :

Permanent loads shrinkage Imposed deformations

1,1 0,55 1,5

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Plate buckling and shear lag

Effectivep width (plate buckling)

effectives width (shear lag)

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Effectives width of concrete slab (ULS and SLS)

bei  min(

be1

b1

b1

Le ; bi ) 8

beff b0

be2

b2

Effectives width of stiffened plates Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

1.2

Shear lag at ULS: 3 alternatives, black one recommended beta (alpha0,x)

 ( 1.4  x )

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1.2

beta élastique en fonction du raidissage



1

0.8

 ( 1 x)

Shear lag atelu SLS: ( 1.4  x ) elastic (red line)

0.6

0.4

0.2



0.083056 0 0 01/50

0.2

0.4

0.6 x x

0.8

b0/Le

1 1.

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Composite cross-section verification at ULS (M>0) fck/gc

0,85 fck/gc

compression



 PNA

ENA



traction

fy/gM Elastic resistance (for class 1, 2, 3)



fy/gM plastic resistance (for classes 1/2)

NOTE : gM is 1.0 (recommended for resistance formulae)

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Verification at SLS • Limitation of stresses for steel and composite bridges – As in EN1992-2 and EN1993-2 (fy in the steel part) • Limitation of crack widths for composite bridges – As in EN1992-2 with tension stiffening (wk=0.3mm in general) – Using a simplified method

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Treatment of instabilities Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

expérimental behaviour

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mechanical model

Aeff

M

equ

=0 

V

P

2=-cr

1  1

2

Principle of verification Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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 u = ultimate loading (without instability)/ ULS loading  cr = critical loading / ULS loading  

u  cr

PRd=PRk/gM

  f ( ) Test /theory (mechanical model) calibration

PRk   Pu

NOTE : gM is 1.1 (recommended for « stability » formulae)

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Plate buckling of stiffened plates in EC3

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Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Fatigue verification in EC3 Calculation of DE,2 under a fatigue loading

P = 480kN

• Influence of the type of influence line • Influence of the type of traffic • Influence of the number of lanes

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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partial factor for loading= 1,0

verification

Dc =80 Category of detail

Orthotropic decks : recommended detailing Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

Deck plate thickness in the carriage way in the heavy vehicle lane t ≥ 14 mm for asphalt layer ≥ 70 mm

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© SETRA

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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1st bridge entirely designed to EC4 in Avignon 4500 t

© SETRA

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

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Outstanding composite bridges Max span 144 m: Verrières viaduct (composite box-girder bridge) © SETRA

Max S460 thickness 120 mm: Guarrigue viaduct © SETRA

© SETRA

Surface > 20000 m²: Vézère viaduct

Seminar ‘Bridge Design with Eurocodes’ – JRC Ispra, 1-2 October 2012

SOME INNOVATIONS / ECONOMY ISSUES

• • • • • • •

Enormous scientific work Simplicity of calculations Robustness (fatigue + brittle fracture) Full exploitation of the materials (postcritical range) Steels up to S690 Hybrid girders Harmonization of the format and the reliability of all the instability formulae • Treatment of stiffened plates • Design of orthotropic decks

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